Organic electroluminescence device

ABSTRACT

Provided is an organic electroluminescence device having a low drive voltage and excellent durability. Provided also is an organic electroluminescence device having low dependency of voltage increment after driving on temperature of usage environment. A light emitting organic thin film containing at least one compound represented by Formula (PQ-1) and a hydrocarbon compound having a specific structure, and an organic electroluminescence device using the same. In Formula (PQ-1), each of R a , R b  and R c  independently represents a hydrogen atom or an alkyl group, wherein any one of R a , R b  and R c  represents a hydrogen atom and the remaining two represent an alkyl group. Each of R 1  to R 5  independently represents a hydrogen atom, an alkyl group, an aryl group, a fluorine atom or a cyano group. Each of R x  and R y  independently represents an alkyl group or a phenyl group.

TECHNICAL FIELD

The present invention relates to an organic electroluminescence device(hereinafter, referred to as “device” or “organic EL device”), as wellas to a display apparatus and illumination apparatus using the same.Particularly, the present invention relates to development of a devicethat is excellent from the viewpoints of efficiency, durability andelectric power consumption, and shows a small variation incharacteristics depending on temperature of usage environment.

BACKGROUND ART

Since organic electroluminescence devices are capable of obtaining alight emission with high luminance intensity by low-voltage driving, thedevices have been actively researched and developed. In general, organicelectroluminescence devices have an organic layer including a lightemitting layer and a pair of electrodes with the organic layerinterposed therebetween, and utilize, for light emission, energy of theexciton generated as a result of recombination of electrons injectedfrom a cathode and holes injected from an anode in the light emittinglayer.

Improvement in the efficiency of devices has been recently made by usinga phosphorescence emitting material. As a phosphorescence emittingmaterial, iridium complexes, platinum complexes and the like are known(see, for example, Patent Document 1).

In addition, doped devices using a light emitting layer including a hostmaterial doped with a light emitting material have been utilized widely.Development of host materials has been conducted actively and aninvention using an aromatic polycyclic condensed ring-based material asa host material has been known (see Patent Document 2, for example).Further, with regard to a phosphorescent material, an invention relatedto a light emitting spectrum with high color purity obtained byintroducing a substituent to a specific position has been known (seePatent Document 3).

Devices have insufficient external quantum efficiency and durability,and require further improvement in their characteristics. Moreover, anincrement in driving voltage caused by temperature of usage environmentbecomes an additional problematic obstacle in practice, and animprovement in such a problem is needed.

Patent Document 2 discloses use of a chrysene derivative as a hostmaterial for the purpose of fabrication of a device with high efficiencyand long service life. In addition, Patent Document 3 discloses use ofIr complexes of phenylquinoline-based ligands having a substituent at aspecific position in a high-performance red phosphorescence device.Further, Patent Document 4 discloses an embodiment in which a chrysenederivative is used as a host material for Ir complexes of specificphenylquinoline-based ligands, but no studies have been conducted abouta difference in driving voltage increment upon driving under differentdriving environments, and thus, such an embodiment is highly problematicin practice.

RELATED ART Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2005-220136-   Patent Document 2: International Publication No. WO 09/008,311-   Patent Document 3: US Patent Application No. 2008/0261076-   Patent Document 4: Japanese Patent Application Laid-Open No.    2009-99783

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

In the devices according to the related art, a difference in drivingvoltage increment at different driving temperatures causes a severeproblem, and thus, an improvement is needed.

The present inventors have found out that, when the host materialincluding a chrysene structure according to the present invention iscombined with a specific iridium complex material, high efficiency, lowdriving voltage or an effect of improving durability are realized, andsimultaneously, dependency of an increment in post-driving voltage ontemperature of usage environment is low.

Therefore, an object of the present invention is to provide an organicelectroluminescence device which has high external quantum efficiency,low driving voltage and excellent durability, and to provide an organicelectroluminescence device which shows low dependency of an increment inpost-driving voltage on temperature of usage environment.

Another object of the present invention is to provide a composition, alight emitting organic thin film and a light emitting layer for use inan organic electroluminescence device. Moreover, still another object ofthe present invention is to provide a method for forming a film of acompound useful for an organic electroluminescence device. Yet anotherobject of the present invention is to provide a light emission apparatusand an illumination apparatus, including the organic electroluminescencedevice.

SUMMARY OF THE INVENTION

That is, the present invention may be accomplished by the followingmeans.

[1] A light emitting organic thin film including at least one compoundrepresented by Formula (PQ-1) and at least one compound represented byFormula (Ch-1).

(In Formula (PQ-1), each of R^(a), R^(b) and R^(c) independentlyrepresents a hydrogen atom or an alkyl group, wherein any one of R^(a),R^(b) and R^(c) represents a hydrogen atom and the remaining tworepresent alkyl groups. Each of R¹ to R⁵ independently represents ahydrogen atom, an alkyl group, an aryl group, a fluorine atom or a cyanogroup. Each of R^(x) and R^(y) independently represents an alkyl groupor a phenyl group.

In Formula (Ch-1), each of R¹⁰¹ to R¹¹⁰ independently represents ahydrogen atom, an alkyl group, a cycloalkyl group or an aryl group. Eachof R¹¹¹ to R¹¹⁵ independently represents a hydrogen atom, an alkylgroup, a cycloalkyl group or an aryl group, with the proviso that anyone of R¹¹¹ to R¹¹⁵ represents a condensed hydrocarbyl group that mayhave a substituent Z. Each of R¹²¹ to R¹²⁵ independently represents ahydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, withthe proviso that any one of R¹²¹ to R¹²⁵ represents a condensedhydrocarbyl group that may have a substituent Z.

The substituent Z represents an alkyl group, an alkenyl group, an arylgroup, an aromatic heterocyclic group, an alkoxy group, an aryloxygroup, a fluorine atom, a silyl group, an amino group, a cyano group ora combination thereof, and a plurality of substituents Z may be bondedto each other to form an aryl ring.)

[2] The light emitting organic thin film of [1], wherein the compoundrepresented by Formula (Ch-1) has no peak current value at 100K to 150Kas determined by thermally stimulated current of a thin film formed to afilm thickness of 100 nm by vacuum deposition of the compound.

[3] The light emitting organic thin film of [1] or [2], wherein, inFormula (PQ-1), two of R^(a), R^(b) and R^(c) represent a methyl groupand the remaining one represents a hydrogen atom.

[4] The light emitting organic thin film of [1] or [2], wherein, inFormula (PQ-1), R^(a) and R^(c) represent an alkyl group and R^(b)represents a hydrogen group.

[5] The light emitting organic thin film of [3] or [4], wherein, inFormula (PQ-1), R¹ to R⁵ represent a hydrogen atom.

[6] The light emitting organic thin film of any one of [1] to [5],wherein, in Formula (Ch-1), R¹⁰¹ to R¹¹⁰ represent a hydrogen atom.

[7] The light emitting organic thin film of any one of [1] to [6],wherein, in Formula (Ch-1), any one of R¹¹¹ to R¹¹⁵ represents anaphthyl or a phenanthryl group and the others represent a hydrogenatom, and any one of R¹²¹ to R¹²⁵ represents a naphthyl or a phenanthrylgroup and the others represent a hydrogen atom.

[8] The light emitting organic thin film of any one of [1] to [7],wherein in Formula (PQ-1), R^(a) and R^(c) represent an alkyl group andR^(b) represents a hydrogen group, and in Formula (Ch-1), any one ofR¹¹¹ to R¹¹⁵ represents a naphthyl or a phenanthryl group and the othersrepresent a hydrogen atom, and any one of R¹²¹ to R¹²⁵ represents anaphthyl or a phenanthryl group and the others represent a hydrogenatom.

[9] The light emitting organic thin film of any one of [1] to [8],wherein a content of Cl, Br and I contained in the light emittingorganic thin film is 100 ppm or less.

[10] A composition including the compound represented by Formula (PQ-1)and the compound represented by Formula (Ch-1) of any one of [1] to [9].

[11] An organic electroluminescence device having a pair of electrodes,and an organic layer including a light emitting layer disposed betweenthe electrodes, on a substrate, wherein the light emitting layer is thelight emitting organic thin film of [1].

[12] An organic electroluminescence device having a pair of electrodes,and an organic layer including a light emitting layer disposed betweenthe electrodes on a substrate, wherein the light emitting layer is thelight emitting organic thin film of [1], and the compound represented byFormula (Ch-1) of [1] has no peak current value at 100K to 150K asdetermined by thermally stimulated current of a thin film formed to afilm thickness of 100 nm by vacuum deposition of the compound.

[13] The organic electroluminescence device of [11] or [12], wherein atleast one layer of the organic layer is formed by a coating processusing a solution or dispersion.

[14] A display apparatus using the organic electroluminescence device ofany one of [11] to [13].

[15] An illumination apparatus using the organic electroluminescencedevice of any one of [11] to [13].

The organic electroluminescence device of the present invention has lowelectric power consumption and high external quantum efficiency, andshows excellent durability. Further, the organic electroluminescencedevice of the present invention has a small difference in voltageincrement even under different driving temperatures, and may exhibitstable performance in use of which the driving durability is required ina high temperature environment, such as an in-vehicle use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating an example of the configurationof an organic EL device according to the present invention (the firstembodiment).

FIG. 2 is a schematic view illustrating an example of a light emittingapparatus according to the present invention (the second embodiment).

FIG. 3 is a schematic view illustrating an example of an illuminationapparatus according to the present invention (the third embodiment).

DESCRIPTION OF EMBODIMENTS

In the present invention, the substituent Z represents an alkyl group,an alkenyl group, an aryl group, an aromatic heterocyclic group, analkoxy group, an aryloxy group, a fluorine atom, a silyl group, an aminogroup, a cyano group or a combination thereof, and a plurality ofsubstituents Z may be bonded to each other to form an aryl ring.

In addition, a hydrogen atom in the following descriptions of Formulae(PQ-1) to (PQ-2), and Formula (Ch-1), also includes isotopes (adeuterium atom and the like), and furthermore, an atom constituting asubstituent also includes isotopes thereof.

In the present invention, “the number of carbon atoms” of a substituent,such as an alkyl group, is used as a meaning to include the case wherethe substituent such as an alkyl group may be substituted with anadditional substituent, and to include the number of carbon atoms of theadditional substituent as well.

The composition and the light emitting organic thin film of the presentinvention include at least one compound represented by Formula (PQ-1)and at least one compound represented by Formula (Ch-1).

The organic electroluminescence device of the present invention includesa pair of electrodes and a light emitting layer between the electrodes,on a substrate, wherein the light emitting layer is the light emittingorganic thin film.

It is possible to obtain an organic electroluminescence device havinglow electric power consumption and high external quantum efficiency andshowing excellent durability by using a compound represented by Formula(PQ-1) and a compound represented by Formula (Ch-1) in the lightemitting layer. It is also possible to obtain an organicelectroluminescence device having a small difference in voltageincrement even under different driving temperatures.

[Compound Represented by Formula (PQ-1)]

The compound represented by Formula (PQ-1) will be described. Since thered phosphorescent compound has high quantum efficiency, a device withhigh luminous efficiency may be realized desirably when used incombination with a compound represented by Formula (Ch-1). Although themechanism is not clear, it is possible to obtain a device that has asmall difference in driving voltage increment even when used at adifferent temperature and is preferable in practice.

(In Formula (PQ-1), each of R^(a), R^(b) and R^(c) independentlyrepresents a hydrogen atom or an alkyl group, wherein any one of R^(a),R^(b) and R^(c) represents a hydrogen atom and the remaining tworepresent an alkyl group. Each of R¹ to R⁵ independently represents ahydrogen atom, an alkyl group, an aryl group, a fluorine atom or a cyanogroup. Each of R^(x) and R^(y) independently represents an alkyl groupor a phenyl group.)

Each alkyl group represented by R^(a), R^(b) and R^(c), and R¹ to R⁵ mayindependently have a substituent, and may be saturated or unsaturated.When the alkyl group has a substituent, the substituent may include thesubstituent Z, preferably an alkyl group, a phenyl group or a fluorineatom, and more preferably an alkyl group. The alkyl group represented byR^(a), R^(b) and R^(c) is an alkyl group having preferably 1 to 8 carbonatoms, more preferably 1 to 5 carbon atoms, such as a methyl group, anethyl group, an n-propyl group, an isopropyl group, an isobutyl group, at-butyl group, an n-butyl group, a cyclohexyl group or the like,preferably a methyl group, an ethyl group, an isobutyl group or at-butyl group, more preferably a methyl group or an ethyl group, andeven more preferably a methyl group.

Each aryl group represented by R¹ to R⁵ may independently be a condensedring, and may have a substituent. The aryl group represented by R¹ to R⁵represents an aryl group having preferably 6 to 12 carbon atoms, morepreferably 6 to 10 carbon atoms, such as a phenyl group or a naphthylgroup, preferably a phenyl group.

In Formula (PQ-1), any one of R^(a), R^(b) and R^(c) represents ahydrogen atom and the remaining two represent an alkyl group.Preferably, R^(b) or R^(c) represents a hydrogen atom, and morepreferably R^(b) represents a hydrogen atom.

In Formula (PQ-1), it is preferred that two of R^(a), R^(b) and R^(c)represent a methyl group, and the remaining one represents a hydrogenatom.

More preferably, R^(a) and R^(c) represent an alkyl group and R^(c)represents a hydrogen group, and even more preferably, R^(a) and R^(c)represent a methyl group and R^(b) represents a hydrogen group.

It is preferred that R¹ to R⁵ represent a hydrogen atom.

Each alkyl group represented by R^(X) and R^(Y) may independently have asubstituent, and may be saturated or unsaturated. When the alkyl grouphas a substituent, the substituent may include the substituent Z,preferably a phenyl group, an aromatic heterocyclic group, a fluorineatom, a silyl group, an amino group, a cyano group or a combinationthereof, and more preferably a phenyl group, a fluorine atom or a cyanogroup. The alkyl group represented by R^(X) and R^(Y) is an alkyl grouphaving preferably 1 to 8 carbon atoms, more preferably 1 to 5 carbonatoms, such as a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an isobutyl group, a t-butyl group, an n-butyl group, acyclohexyl group, or the like, preferably a methyl group, an ethylgroup, an isobutyl group or a t-butyl group, more preferably a methylgroup.

The alkyl group represented by the substituent Z is an alkyl grouppreferably having 1 to 8 carbon atoms, more preferably 1 to 5 carbonatoms, such as a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an isobutyl group, a t-butyl group, an n-butyl group, acyclopropyl group, or the like, preferably a methyl group, an ethylgroup, an isobutyl group or a t-butyl group, and more preferably amethyl group.

The alkenyl group represented by the substituent Z is an alkenyl grouppreferably having 2 to 8 carbon atoms, more preferably 2 to 5 carbonatoms, such as a vinyl group, an n-propenyl group, an isopropenyl group,an isobutenyl group, an n-butenyl group, or the like, and preferably avinyl group or an n-propenyl group.

The aryl group represented by the substituent Z is an aryl grouppreferably having 6 to 30 carbon atoms, such as a phenyl group, anaphthyl group, an anthracenyl group, a tetracenyl group, a pyrenylgroup, a perylenyl group, a triphenylenyl group or a chrysenyl group,and more preferably a phenyl group, a naphthyl group, an anthracenylgroup or a chrysenyl group.

The aromatic heterocyclic group represented by the substituent Z is anaromatic heterocyclic group preferably having 4 to 30 carbon atoms, suchas a pyridine, a pyrazine, a pyrimidine, a pyridazine, a triazine, athiophene, a furan, an oxazole, a thiazole, an imidazole, a pyrazole, atriazole, an oxadiazole, a thiadiazole, or the like.

The alkoxy group represented by the substituent Z is an alkoxy grouppreferably having 1 to 8 carbon atoms, more preferably 1 to 5 carbonatoms, such as a methoxy group, an ethoxy group, an n-propyloxy group,an isopropyloxy group, or the like, preferably a methoxy group or anethoxy group, and more preferably a methoxy group.

The aryloxy group represented by the substituent Z is an aryloxy grouppreferably having 6 to 30 carbon atoms, such as a phenoxy group or anaphthoxy group, preferably a phenoxy group.

The aryl group formed by a plurality of substituents Z bound with eachother may include a phenyl ring or a pyridine ring, preferably a phenylring.

Preferably, the compound represented by Formula (PQ-1) is a compoundrepresented by the following Formula (PQ-2).

(In Formula (PQ-2), each of R_(a2) and R_(c2) independently representsan alkyl group. Each of R^(X2) and R^(Y2) independently represents analkyl group).

The alkyl group represented by R_(a2) and R_(c2) has the same meaning asdefined for the above R_(a) and R_(c), and preferred ranges thereof arealso the same.

The alkyl group represented by R^(X2) and R^(Y2) has the same meaning asdefined for the above R^(X) and R^(Y) in Formula (PQ-1), and preferredranges thereof are also the same.

Particular examples of the compound represented by Formula (PQ-1) arelisted hereinafter, but are not limited thereto.

Compounds exemplified as the compounds represented by the above Formula(PQ-1) may be synthesized by various methods, for example, a methoddescribed in Japanese Patent No. 3929632, and the like. For example, thecompounds may be synthesized using 2-phenylquinoline as a starting rawmaterial by a method described on page 18, lines 2 to 13 of JapanesePatent No. 3929632, or using 2-(2-naphthyl)quinoline as a starting rawmaterial by a method described on page 18, line 14 to page 19, line 8 ofJapanese Patent No. 3929632.

In the present invention, it is preferable that the compound representedby Formula (PQ-1) is contained in the light emitting organic thin filmin an amount of preferably 0.1 to 30 mass %, preferably 2 to 20 mass %,and particularly preferably 5 to 15 mass % in the light emitting organicthin film.

In addition, it is preferably that each of Cl, Br and I is contained inthe light emitting organic thin film in an amount of 100 ppm or less,more preferably 0 ppm to 40 ppm, and particularly preferably 0 ppm to 10ppm. When each of Cl, Br and I is contained in the light emittingorganic thin film in an amount of 100 ppm or less, it is possible toinhibit deterioration during light emission and to improve thedurability of a device. It is possible to obtain an amount of Cl, Br, Iof 100 ppm or less by repeating purification of materials.

In the present invention, the compound represented by Formula (PQ-1) iscontained in the light emitting organic thin film, but the use thereofis not limited thereto and the compound may be contained in any onelayer of the organic layer.

The compound represented by Formula (Ch-1) will be described.

Since the compound of Formula (Ch-1) has a chrysene structure and is amaterial having high rigidity and durability, a light emitting layer ora luminescence device with high durability and quantum efficiency may berealized when used in combination with a compound represented by Formula(PQ-1). Although the mechanism is not clear, it is possible to fabricatea device that has a small difference in driving voltage increment evenwhen used under different temperatures and is preferable in practice.

[Compound Represented by Formula (Ch-1)]

(In Formula (Ch-1), each of R¹⁰¹ to R¹¹⁰ independently represents ahydrogen atom, an alkyl group, a cycloalkyl group or an aryl group. Eachof R¹¹¹ to R¹¹⁵ independently represents a hydrogen atom, an alkylgroup, a cycloalkyl group or an aryl group, with the proviso that anyone of R¹¹¹ to R¹¹⁵ represents a condensed hydrocarbyl group that mayhave a substituent Z. Each of R¹²¹ to R¹²⁵ independently represents ahydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, withthe proviso that any one of R¹²¹ to R¹²⁵ represents a condensedhydrocarbyl group that may have a substituent Z.)

The alkyl group represented by R¹⁰¹ to R¹¹⁰ represents an alkyl grouppreferably having 1 to 10 carbon atoms, more preferably 1 to 5 carbonatoms, such as a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an isobutyl group, a t-butyl group, an n-butyl group,preferably a methyl group, an ethyl group, an isobutyl group or at-butyl group, and more preferably a methyl group.

The cycloalkyl group represented by R¹⁰¹ to R¹¹⁰ represents a cycloalkylgroup preferably having 3-10 carbon atoms, such as a cyclopropyl group,a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, or thelike, preferably a cyclohexyl group.

In the phenyl group that may have a substituent Z represented by R¹⁰¹ toR¹¹⁰, the substituent Z may be exemplified by the above-describedsubstituent Z. Preferably, the phenyl group that may have a substituentZ, represented by R¹⁰¹ to R¹¹⁰, is a non-substituted phenyl group.

In Formula (Ch-1), R¹⁰¹, R¹⁰², R¹⁰³, R¹⁰⁵, R¹⁰⁶, R¹⁰⁷, R¹⁰⁸ and R¹¹⁰preferably represent a hydrogen atom. R¹⁰⁴ and R¹⁰⁹ preferably representa hydrogen atom, a methyl group, a t-butyl group, a cyclohexyl group, aphenyl group, more preferably a hydrogen atom, a t-butyl group, a phenylgroup, more preferably a hydrogen atom, a phenyl group, and mostpreferably a hydrogen atom.

In Formula (Ch-1), from the viewpoints of the durability of a device,R¹⁰¹ to R¹¹⁰ preferably represent a hydrogen atom.

An alkyl group, a cycloalkyl group and a phenyl group that may have asubstituent Z, represented by R¹¹¹ to R¹¹⁵ and R¹²¹ to R¹²⁵ have thesame meanings as defined for R¹⁰¹ to R¹¹⁰, and preferred ranges are alsothe same.

However, any one of R¹¹¹ to R¹¹⁵ represents a condensed hydrocarbylgroup that may have a substituent Z, preferably a condensed hydrocarbylgroup having 10 to 20 carbon atoms. The condensed hydrocarbyl group thatmay have a substituent Z is a naphthyl group, a phenanthryl group, atriphenylenyl group, an anthracenyl group, a tetracenyl group, achrysenyl group, more preferably a naphthyl group, a phenanthryl group,a triphenylenyl group, even more preferably a naphthyl group or aphenanthryl group, and more preferably a naphthyl group.

The condensed hydrocarbyl group that may have a substituent Z ispreferably any one of R¹¹², R¹¹³, R¹¹⁴, particularly preferably is R¹¹³.

In addition, any one of R¹²¹ to R¹²⁵ represents a condensed hydrocarbylgroup that may have a substituent Z, preferably a condensed hydrocarbylgroup having 10 to 20 carbon atoms. The condensed hydrocarbyl group thatmay have a substituent Z is a naphthyl group, a phenanthryl group, atriphenylenyl group, an anthracenyl group, a tetracenyl group, achrysenyl group, more preferably a naphthyl group, a phenanthryl group,a triphenylenyl group, even more preferably a naphthyl group or aphenanthryl group, and more preferably a naphthyl group.

The condensed hydrocarbyl group that may have a substituent Z ispreferably any one of R¹²², R¹²³, R¹²⁴, particularly preferably is R¹²³.

In Formula (Ch-1), from the viewpoints of the durability of a device, itis preferably that any one of R¹¹¹ to R¹¹⁵ is a naphthyl group or aphenanthryl group and the others are a hydrogen atom, and any one ofR¹²¹ to R¹²⁵ is a naphthyl group or a phenanthryl group and the othersare a hydrogen group.

It is preferable that the compound represented by Formula (Ch-1) has nopeak current value at 100K to 150K as determined by thermally stimulatedcurrent of a thin film formed to a film thickness of 100 nm by vacuumdeposition of the compound represented by Formula (Ch-1). The fact thatthe compound has no peak current value at 100 L to 150 K means that thecompound has no trap level participating in conductivity in thecorresponding thin film, and thus, the compound inhibits deteriorationcaused by charges trapped at the trap level, thereby contributing toimprovement of the durability of a device.

Herein, measurement of thermally stimulated current may be carried outby a thermally stimulated current analyzer, TS-FETT, available fromRigaku Denki Co., Ltd.

The compound represented by Formula (Ch-1) preferably has a molecularweight of 400 to 1000, more preferably 450 to 800, and even morepreferably 500 to 700.

The compound represented by Formula (Ch-1) preferably has a glasstransition temperature (Tg) of 80° C. to 400° C., more preferably 100°C. to 400° C., and even more preferably 120° C. to 400° C.

When Formula (Ch-1) has a hydrogen atom, such a hydrogen atom alsoincludes isotopes (a deuterium atom and the like). In this case, allhydrogen atoms in the compound may be substituted by isotopes, or thecompound may be a mixture partially containing isotopes.

Hereinafter, particular examples of the compound represented by Formula(Ch-1) will be exemplified but the present invention is not limitedthereto. In addition, in the following particular examples, Phrepresents a phenyl group and Me represents a methyl group.

Compounds exemplified as the compounds represented by the above Formula(Ch-1) may be synthesized by applying a method described in InternalPatent Publication No. WO 09/008311.

In the present invention, the compound represented by Formula (Ch-1) iscontained in a light emitting organic thin film. In the light emittingdevice of the present invention, use of the compound is not limited andthe compound may be further contained in any one layer within theorganic layer. Preferably, the compound represented by Formula (Ch-1)may be introduced to one or more layers among a light emitting layer, ahole injection layer, a hole transporting layer, an electrontransporting layer, an electron injection layer, an exciton blockinglayer and a charge blocking layer.

In the organic thin film of the present invention, it is preferablethat, in Formula (PQ-1), R^(a) and R^(c) represents an alkyl group andR^(b) represents a hydrogen atom, and in Formula (Ch-1), any one of R¹¹¹to R¹¹⁵ is a naphthyl group or a phenanthryl group and the others are ahydrogen atom, and any one of R¹²¹ to R¹²⁵ is a naphthyl group or aphenanthryl group and the others are a hydrogen atom.

The content of the compound represented by Formula (Ch-1) in the lightemitting organic thin film of the present invention is preferably 0.1 to99 mass %, more preferably 1 to 95 mass %, and even more preferably 10to 95 mass %, based on the total mass of the light emitting organic thinfilm.

In addition, in the light emitting device of the present invention, inthe case of the compound represented by Formula (Ch-1) contained in anyone layer other than the light emitting layer formed of the lightemitting organic thin film, the content is preferably 10 to 100 mass %,more preferably 30 to 100 mass %, and even more preferably 50 to 100mass %.

[Light Emitting Layer Containing a Compound Represented by Formula(PQ-1) and a Compound Represented by Formula (Ch-1)]

The present invention also relates to a light emitting layer containinga compound represented by Formula (PQ-1) and a compound represented byFormula (Ch-1). The light emitting layer of the present invention may beapplied to an organic electroluminescence device.

[Composition Containing a Compound Represented by Formula (PQ-1) and aCompound Represented by Formula (Ch-1)]

The present invention also relates to a composition containing acompound represented by Formula (PQ-1) and a compound represented byFormula (Ch-1).

In the composition of the present invention, the content of the compoundrepresented by Formula (PQ-1) is preferably 1 to 40 mass %, and morepreferably 5 to 20 mass %.

In the composition of the present invention, the content of the compoundrepresented by Formula (Ch-1) is preferably 50 to 95 mass %, and morepreferably 70 to 90 mass %.

Other ingredients that may be further contained in the composition ofthe present invention may be organic materials or inorganic materials,and the materials exemplified as host materials, fluorescence emittingmaterials, phosphorescence emitting materials and hydrocarbon materialshereinafter may be used as the organic materials.

The composition of the present invention may form an organic layer of anorganic electroluminescence device by a dry film forming method such asdeposition or sputtering, or by a wet film forming method such asink-jet, spin coating, bar coating, transferring or printing.

Further, the present invention relates to a method for selection of acompound represented by Formula (Ch-1) for use in a light emitting layerof an organic electroluminescence device having a pair of electrodes,and an organic layer including a light emitting layer disposed betweenthe electrodes on a substrate, wherein the light emitting layer containsa compound represented by Formula (PQ-1) and a compound represented byFormula (Ch-1), characterized by selecting a compound having no peakcurrent value at 100K to 150K as determined by thermally stimulatedcurrent of a thin film formed to a film thickness of 100 nm by vacuumdeposition of the compound. By the selection, it is possible to providea device with higher durability.

[Organic Electroluminescence Device]

The device of the present invention will be described in detail.

The organic electroluminescence device of the present invention has, ona substrate, a pair of electrodes and a light emitting layer between theelectrodes, wherein the light emitting layer is the light emittingorganic thin film of the present invention. The light emitting organicthin film of the present invention contains a compound represented byFormula (Ch-1) and a compound represented by Formula (PQ-1).

In the organic electroluminescence device of the present invention, thelight emitting layer is an organic layer and the device may have aplurality of organic layers.

Due to properties of the luminescence device, at least one electrode ofthe anode and the cathode is preferably transparent or semi-transparent.

FIG. 1 shows an example of the configuration of an organicelectroluminescence device according to the present invention. Theorganic electroluminescence device 10 of the present invention as shownin FIG. 1, has a light emitting layer 6 between an anode 3 and a cathode9 on a supporting substrate 2. Particularly, a hole injection layer 4, ahole transporting layer 5, a light emitting layer 6, a hole blockinglayer 7, and an electron transporting layer 8 are laminated in thisorder between the anode 3 and the cathode 9.

<Configuration of Organic Layer>

There is no particular limitation in the configuration of the organiclayer, and the organic layer may be selected adequately depending on theuse and purpose of an organic electroluminescence device, but it ispreferred to be formed on the transparent electrode or on the backelectrode. In this case, the organic layer is formed on the frontsurface or one surface of the transparent electrode or the backelectrode.

The shape, size and thickness of the organic layer are not particularlylimited and may be selected adequately depending on the purpose.

Particular examples of the configuration will be described hereinafterbut the present invention is not limited thereto.

-   -   Anode/hole transporting layer/light emitting layer/electron        transporting layer/cathode,    -   Anode/hole transporting layer/light emitting layer/second        electron transporting layer (hole blocking layer)/first electron        transporting layer/cathode,    -   Anode/hole transporting layer/light emitting layer/second        electron transporting layer (hole blocking layer)/first electron        transporting layer/electron injection layer/cathode,    -   Anode/hole injection layer/hole transporting layer (electron        blocking layer)/light emitting layer/second electron        transporting layer (hole blocking layer)/first electron        transporting layer/cathode,    -   Anode/hole injection layer/first hole transporting layer/second        hole transporting layer (electron blocking layer)/light emitting        layer/second electron transporting layer (hole blocking        layer)/first electron transporting layer/cathode.

The device configuration, substrate, cathode, and anode of the organicelectroluminescence device are described in detail in, for example,Japanese Patent Application Laid-Open No. 2008-270736, and the subjectmatters described in the publication may be applied to the presentinvention.

<Substrate>

It is preferred that the substrate used in the present invention is asubstrate which does not scatter or decay light generated from theorganic layer. In the case of organic materials, those excellent in heatresistance, dimensional stability, solvent resistance, electricalinsulating property and processability are preferred.

<Anode>

Typically, the anode may have a function as an electrode for supplying ahole into the organic layer. The anode is not particularly limited withrespect to a shape, a structure, a size and the like, and may beappropriately selected among known electrode materials depending upon ause or purpose of the luminescence device. As described above, the anodeis usually provided as a transparent anode.

<Cathode>

Typically, the cathode may have a function as an electrode for injectingan electron into the organic layer. The cathode is not particularlylimited with respect to a shape, a structure, a size and the like, andmay be appropriately selected among known electrode materials dependingupon a use or purpose of the luminescence device.

With respect to the substrate, the anode and the cathode, the subjectmatters described in paragraph Nos. [0070] to [0089] of Japanese PatentApplication Laid-Open No. 2008-270736 may be applied to the presentinvention.

<Organic Layer>

The organic layer of the present invention will be described in detail.

Formation of Organic Layer

In the organic electroluminescence device of the present invention, eachorganic layer may be formed suitably by any one of dry film formingmethods, such as deposition or sputtering, and coating processes, suchas transfer coating, printing, inkjet coating, spin coating, barcoating, and the like.

(Light Emitting Layer)

<Light Emitting Material>

It is preferred that the light emitting material in the invention is acompound represented by Formula (PQ-1).

The light emitting material in the light emitting layer is generallycontained in an amount of 0.1 mass % to 50 mass % based on the totalmass of the compounds forming the light emitting layer. However, fromthe viewpoints of durability and external quantum efficiency, thematerial is contained in an amount of preferably 1 mass % to 50 mass %,more preferably 2 mass % to 40 mass %.

A thickness of the light emitting layer is not particularly limited, buttypically, is preferably 2 nm to 500 nm, and among them, from theviewpoint of external quantum efficiency, the thickness of the lightemitting layer is more preferably 3 nm to 200 nm, and even morepreferably 5 nm to 100 nm.

The light emitting material in the device of the present invention mayfurther include any light emitting layer other than the light emittinglayer of the present invention, and such a light emitting layer may becomposed of a light emitting material alone or a combination of a hostmaterial with a light emitting material. The light emitting material maybe a fluorescence emitting material or a phosphorescence emittingmaterial, and one kind of dopant or two or more kinds of dopants may beused. Preferably, the host material is a charge transporting material.One kind of host material or two or more kinds of host materials may beused, and for example, a combination of an electron transporting hostmaterial with a hole transporting host material may be used. Inaddition, a material having no charge transportability and lightemitting property may be contained in the light emitting layer. In thelight emitting layer of the device of the present invention, acombination using a compound represented by Formula (Ch-1) and acompound represented by Formula (PQ-1) are essentially contained as thehost material.

In addition, the light emitting layer may be a single layer ormultilayer having two layers or more. In the case of a multilayeredlight emitting layer, a compound represented by Formula (Ch-1) and acompound represented by Formula (PQ-1) may be contained in two or morelight emitting layers. Further, each light emitting layer may emit adifferent color.

<Host Material>

As the host material used in the present invention, the compoundrepresented by Formula (Ch-1) is preferred.

The compound represented by Formula (Ch-1) can transport positive andnegative charges, such as holes and electrons, and makes a carrierbalance between holes and electrons better through the combination witha compound represented by Formula (PQ-1). Therefore, although thecompound has a carbazole group, it is possible to improve drivingdurability. Further, even at a different driving temperature, it ispossible to reduce a difference in voltage increment.

As the host material used in the present invention, the compounds listedhereinafter may be further contained. For example, examples thereof mayinclude, for example, conductive polymer oligomers such as a pyrrole, anindole, a carbazole, a CBP (4,4′-di(9-carbazoyl)biphenyl), an azaindole,an azacarbazole, a triazole, an oxazole, an oxadiazole, a pyrazole, animidazole, a thiophene, a polyarylalkane, a pyrazoline, a pyrazolone, aphenylenediamine, an arylamine, an amino-substituted chalcone, astyrylanthracene, a fluorenone, a hydrazone, a stilben, a silazane, anaromatic tertiary amine compound, a styrylamine compound, apolypyrine-based compound, a polysilane-based compound, apoly(N-vinylcarbazole), an aniline-based copolymer, a thiopheneoligomer, and a polythiophene, organosilane, a carbon film, a pyridine,a pyrimidine, a triazine, an imidazole, a pyrazole, a triazole, anoxazole, an oxadiazole, a fluorenone, an anthraquinodimethane, ananthrone, a diphenylquinone, a thiopyrane dioxide, a carbodiimide, afluorenylidene methane, a distyrylpyrazine, a fluoro-substitutedaromatic compound, a heterocyclic tetracarboxylic acid anhydrides suchas a naphthalene, a perylene, or the like, a phthalocyanine, a metalcomplex of 8-quinolinol derivatives or a metal phthalocyanine, variousmetal complexes represented by metal complexes having a benzoxazole or abenzothiazole as a ligand, and a derivative (which may have asubstituent or a condensed ring) thereof.

In the light emitting layer of the present invention, it is preferablethat a lowest triplet excited state (T₁) energy of the host material(also containing the compound represented by Formula (Ch-1)) is higherthan T₁ energy of the phosphorescence emitting material, from theviewpoints of color purity, luminous efficiency and driving durability.

In addition, a content of the host compound in the present invention isnot particularly limited, but is preferably 15 mass % to 95 mass % basedon the total mass of the compounds forming the light emitting layer,from the viewpoints of luminous efficiency and driving voltage.

When the compound represented by Formula (Ch-1) is introduced to a layer(e.g. a charge transporting layer) other than a light emitting layer,the compound is contained in the layer preferably in an amount of 10mass % to 100 mass %, and more preferably 30 mass % to 100 mass %.

(Fluorescence Emitting Material)

Examples of the fluorescence emitting material that may be used in thepresent invention include benzoxazole derivatives, benzoimidazolederivatives, benzothiazole derivatives, styrylbenzene derivatives,polyphenyl derivatives, diphenylbutadiene derivatives,tetraphenylbutaidene derivatives, naphthalimide derivatives, cumarinederivatives, condensed aromatic compounds, perinone derivatives,oxadizaole derivatives, oxazine derivatives, aldazine derivatives,pyralyzine derivatives, cyclopentadiene derivatives, bisstyrylanthracenederivatives, quinacridone derivatives, pyrrolopyridine derivatives,thiadiazopyridine derivatives, cyclopentadiene derivatives, styrylaminederivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidenecompounds, various complexes represented by complexes of 8-quinolinolderivatives or complexes of pyromethene derivatives, polymer compoundssuch as a polythiophene, a polyphenylene, a polyphenylene vinylene, orthe like, compounds such as an organosilane derivative, or the like.

(Phosphorescence Emitting Material)

The phosphorescence emitting materials that may be used in the presentinvention include, besides a compound represented by Formula (PQ-1), forexample, phosphorescence emitting compounds described in patentdocuments, such as U.S. Pat. No. 6,303,238B1, U.S. Pat. No. 6,097,147,WO00/57676, WO00/70655, WO01/08230, WO01/39234A2, WO01/41512A1,WO02/02714A2, WO02/15645A1, WO02/44189A1, WO05/19373A2, Japanese PatentApplication Laid-Open No. 2001-247859, Japanese Patent ApplicationLaid-Open No. 2002-302671, Japanese Patent Application Laid-Open No.2002-117978, Japanese Patent Application Laid-Open No. 2003-133074,Japanese Patent Application Laid-Open No. 2002-235076, Japanese PatentApplication Laid-Open No. 2003-123982, Japanese Patent ApplicationLaid-Open No. 2002-170684, EP1211257, Japanese Patent ApplicationLaid-Open No. 2002-226495, Japanese Patent Application Laid-Open No.2002-234894, Japanese Patent Application Laid-Open No. 2001-247859,Japanese Patent Application Laid-Open No. 2001-298470, Japanese PatentApplication Laid-Open No. 2002-173674, Japanese Patent ApplicationLaid-Open No. 2002-203678, Japanese Patent Application Laid-Open No.2002-203679, Japanese Patent Application Laid-Open No. 2004-357791,Japanese Patent Application Laid-Open No. 2006-256999, Japanese PatentApplication Laid-Open No. 2007-19462, Japanese Patent ApplicationLaid-Open No. 2007-84635, Japanese Patent Application Laid-Open No.2007-96259, or the like, and more preferred light emitting dopants amongthem include Ir complexes, Pt complexes, Cu complexes, Re complexes, Wcomplexes, Rh complexes, Ru complexes, Pd complexes, Os complexes, Eucomplexes, Tb complexes, Gd complexes, Dy complexes and Ce complexes.Particularly preferably, the phosphorescence emitting material is an Ircomplex, Pt complex or Re complex, and among them, an Ir complex, Ptcomplex or Re complex containing at least one coordination type ofmetal-carbon bonding, metal-nitrogen bonding, metal-oxygen bonding andmetal-sulfur bonding is preferred. In addition, from the viewpoints ofluminous efficiency, driving durability, chromaticity, or the like, anIr complex, Pt complex or Re complex containing a tridentate ormulti-dentate ligand is particularly preferred.

A content of the phosphorescence emitting material in the light emittinglayer is preferably 0.1 mass % to 50 mass %, more preferably 0.2 mass %to 50 mass %, even more preferably 0.3 mass % to 40 mass %, and mostpreferably 20 mass % to 30 mass %, based on the total mass of the lightemitting layer.

The content of the phosphorescence emitting material (a compoundrepresented by Formula (PQ-1) and/or a phosphorescence emitting materialused in combination) that may be used in the present invention ispreferably 0.1 mass % to 50 mass %, more preferably 1 mass % to 40 mass%, and most preferably 5 mass % to 30 mass %, based on the total mass ofthe light emitting layer. Particularly, in the range of 5 mass % to 30mass %, the chromaticity of light emission of the corresponding organicelectroluminescence device is less dependent on the concentration of theadded phosphorescence emitting material.

Most preferably, the organic electroluminescence device of the presentinvention contains at least one of compounds represented by Formula(PQ-1) in an amount of 5 to 30 mass % based on the total mass of thelight emitting material.

A thickness of the light emitting layer is not particularly limited, buttypically, is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm,and even more preferably 10 nm to 100 nm.

(Charge Transporting Layer)

A charge transporting layer refers to a layer in which charge transportoccurs when applying voltage to an organic electroluminescence device.Particularly, the charge transporting layer includes a hole injectionlayer, a hole transporting layer, an electron blocking layer, a lightemitting layer, a hole blocking layer, an electron transporting layer oran electron injection layer. Preferably, the charge transporting layeris a hole injection layer, a hole transporting layer, an electronblocking layer or a light emitting layer. When a charge transportinglayer formed by a coating method is a hole injection layer, a holetransporting layer, an electron blocking layer or a light emittinglayer, it is possible to fabricate a low-cost, high-efficiency organicelectroluminescence device. More preferably, the charge transportinglayer is a hole injection layer, a hole transporting layer or anelectron blocking layer.

Hole Injection Layer and Hole Transporting Layer

A hole injection layer and a hole transporting layer are layers having afunction of accepting a hole from an anode or anode side andtransporting the hole to a cathode side.

A hole injection material and a hole transporting material used in theselayers may be a low-molecular weight compound or a polymer compound.

Particularly, it is preferred that the hole injection layer and the holetransporting layer are layers containing a pyrrole derivative, acarbazole derivative, a pyrrole derivative, a triazole derivative, anoxazole derivative, an oxadiazole derivative, an imidazole derivative, apolyarylalkane derivative, a pyrazoline derivative, a pyrazolonederivative, a phenylene diamine derivative, an arylamine derivative, anamino-substituted chalcone derivative, a styrylanthracene derivative, afluorenone derivative, a hydrazone derivative, a stilbene derivative, asilazane derivative, an aromatic tertiary amine compound, a styrylaminecompound, a phthalocyanine-based compound, a polypyrine-based compound,a thiophene derivative, an organosilane derivative, carbon, variousmetal complexes such as an Ir complex, or the like.

An electron-accepting dopant may be contained in the hole injectionlayer or the hole transporting layer in the organic electroluminescencedevice of the present invention. As the electron accepting dopantintroduced to the hole injection layer or the hole transporting layer,any inorganic compound or organic compound may be used as long as thecompound is electron accepting and functions to oxidize an organiccompound.

Particularly, the inorganic compound includes a metal halide such as aferric chloride or an aluminum chloride, a gallium chloride, an indiumchloride, an antimony pentachloride, or the like, and a metal oxide suchas a vanadium pentaoxide, a molybdenum trioxide, or the like.

In the case of an organic compound, a compound having a nitro group, ahalogen, a cyano group, a trifluoromethyl group, or the like as asubstituent, a quinone-based compound, an acid anhydride-based compound,fullerene, or the like may be suitably used.

Besides, compounds described in Japanese Patent Application Laid-OpenNo. Hei 6-212153, Japanese Patent Application Laid-Open No. Hei11-111463, Japanese Patent Application Laid-Open No. Hei 11-251067,Japanese Patent Application Laid-Open No. 2000-196140, Japanese PatentApplication Laid-Open No. 2000-286054, Japanese Patent ApplicationLaid-Open No. 2000-315580, Japanese Patent Application Laid-Open No.2001-102175, Japanese Patent Application Laid-Open No. 2001-160493,Japanese Patent Application Laid-Open No. 2002-252085, Japanese PatentApplication Laid-Open No. 2002-56985, Japanese Patent ApplicationLaid-Open No. 2003-157981, Japanese Patent Application Laid-Open No.2003-217862, Japanese Patent Application Laid-Open No. 2003-229278,Japanese Patent Application Laid-Open No. 2004-342614, Japanese PatentApplication Laid-Open No. 2005-72012, Japanese Patent ApplicationLaid-Open No. 2005-166637, Japanese Patent Application Laid-Open No.2005-209643, or the like may be used adequately.

Among the compounds, a hexacyanobutadiene, a hexacyanobenzene, atetracyanoethylene, a tetracyanoquinodimethane, atetrafluorotetracyanoquinodimethane, a p-fluoranyl, a p-chloranyl, ap-bromanyl a p-benzoquinone, a 2,6-dichlorobenzoquinone, a2,5-dichlorobenzoquinone, a 2,5-dichlorobenzoquinone, a1,2,4,5-tetracyanobenzene, a 1,4-dicyanotetrafluorobenzene, a2,3-dichloro-5,6-dicyanobenzoquinone, a p-dinitrobenzene, am-dinitrobenzene, an o-dinitrobenzene, a 1,4-naphthoquinone, a2,3-dichloronaphthoquinone, a 1,3-dinitronaphthalene, a1,5-dinitronaphthalene, a 9,10-anthraquinone, a1,3,6,8-tetranitrocarbazole, a 2,4,7-trinitro-9-fluorenone, a2,3,5,6-tetracyanopyridine, or a fullerene C60 is preferred, ahexacyanobutadiene, a hexacyanobenzene, a tetracyanoethylene, atetracyanoquinodimethane, a tetrafluorotetracyanoquinodimethane, ap-fluoranyl, a p-chloranyl, a p-bromanyl, a 2,6-dichlorobenzoquinone, a2,5-dichlorobenzoquinone, a 2,3-dichloronaphthoquinone, a1,2,4,5-tetracyanobenzene, a 2,3-dichloro-5,6-dicyanobenzoquinone or a2,3,5,6-tetracyanopyridine is more preferred, and atetrafluorotetracyanoquinodimethane is particularly preferred.

These electron-accepting dopants may be used alone or in combination.The electron-accepting dopants is used in a different amount dependingon the type of a material, but is used preferably in an amount of 0.01mass % to 50 mass %, more preferably 0.05 mass % to 20 mass %, andparticularly preferably 0.1 mass % to 10 mass % based on the holetransporting layer material.

From the viewpoint of lowering the driving voltage, a thickness of eachof the hole injection layer and the hole transporting layer ispreferably 500 nm or less.

The thickness of the hole transporting layer is preferably 1 nm to 500nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to100 nm. Also, the thickness of the hole injection layer is preferably0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and even morepreferably 1 nm to 100 nm.

Each of the hole injection layer and the hole transporting layer mayhave a single layer structure composed of one or two or more kinds ofthe above-described materials, or may have a multilayer structurecomposed of a plurality of layers of the same or different compositions.

Electron Injection Layer and Electron Transporting Layer

The electron injection layer and the electron transporting layer arelayers having a function of accepting electrons from the cathode or thecathode side to transport the electron into the anode side.

With respect to the hole injection layer, the hole transporting layer,the electron injection layer and the electron transporting layer, thesubject matters described in paragraph Nos. [0165] to [0167] of JapanesePatent Application Laid-Open No. 2008-270736 may be applied to thepresent invention.

Hole Blocking Layer

The hole blocking layer is a layer having a function of preventing holestransported from the anode side to the light emitting layer from passingtoward the cathode side. In the present invention, it is possible toprovide the hole blocking layer as an organic layer adjacent to thelight emitting layer at a cathode side.

Examples of organic compounds forming the hole blocking layer includealuminum complexes such as an aluminum (III)bis(2-methyl-8-quinolinato)-4-phenylphenolate (abbreviated as BAlq),triazole derivatives, phenanthroline derivatives such as a2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (abbreviated as BCP), orthe like.

The thickness of the hole blocking layer is preferably 1 nm to 500 nm,more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100nm.

The hole blocking layer may have a single layer structure composed ofone or two or more kinds of the above-described materials, or may have amultilayer structure composed of a plurality of layers of the same ordifferent compositions.

Electron Blocking Layer

The electron blocking layer is a layer having a function of preventingelectrons transported from the cathode side to the light emitting layerfrom passing toward the anode side. In the present invention, it ispossible to provide the electron blocking layer as an organic layeradjacent to the light emitting layer at an anode side.

As examples of organic compounds forming the electron blocking layer,the above-described materials exemplified as the hole transportingmaterial may be applied.

The thickness of the electron blocking layer is preferably 1 nm to 500nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to100 nm.

The electron blocking layer may have a single layer structure composedof one or two or more kinds of the above-described materials, or mayhave a multilayer structure composed of a plurality of layers of thesame or different compositions.

<Protective Layer>

In the present invention, the whole of the organic EL device may beprotected with a protective layer.

With respect to the protective layer, the subject matters described inparagraph No. [0169] to [0170] of Japanese Patent Application Laid-OpenNo. 2008-270736 may be applied to the present invention.

<Sealing Container>

In the device of the present invention, the whole device may be sealedusing a sealing container.

With respect to the sealing container, the subject matters described inparagraph No. [0171] of Japanese Patent Application Laid-Open No.2008-270736 may be applied to the present invention.

(Driving)

In the organic electroluminescence device of the present invention,light emission may be obtained by applying a DC voltage (typically 2volts to 15 volts) (which may include an alternating current componentif necessary) or a direct current between the anode and the cathode.

With respect to the driving method of the organic electroluminescencedevice of the present invention, driving methods described in JapanesePatent Application Laid-Open No. Hei 2-148687, Japanese PatentApplication Laid-Open No. Hei 6-301355, Japanese Patent ApplicationLaid-Open No. Hei 5-29080, Japanese Patent Application Laid-Open No. Hei7-134558, Japanese Patent Application Laid-Open No. Hei 8-234685, andJapanese Patent Application Laid-Open No. Hei 8-241047, and JapanesePatent No. 2784615, U.S. Pat. No. 5,828,429, and U.S. Pat. No.6,023,308, or the like may be applied.

In the luminescence device of the present invention, it is possible toenhance light extraction efficiency by various known methods. Forexample, refractive indexes of a substrate, ITO layer and an organiclayer are controlled by treating (e.g. forming a fine surfaceirregularity pattern) the surface shape of the substrate. It is alsopossible to improve external quantum efficiency through the enhancementof light extraction efficiency, for example, by controlling thicknessesof a substrate, ITO layer and an organic layer.

The external quantum efficiency of the organic electroluminescencedevice of the present invention is preferably 20% to 30%. As a value ofexternal quantum efficiency, a maximum value of external quantumefficiency when driving the device at 20° C., or a value of externalquantum efficiency near 100 to 300 cd/m² when driving the device at 20°C. may be used.

The luminescence device of the present invention may be in a so-calledtop emission system of extracting light from the anode side.

The organic EL device of the present invention may have a resonatorstructure. For example, a multilayer mirror composed of a plurality oflaminated films differing in the refractive index, a transparent orsemi-transparent electrode, a light emitting layer, and a metalelectrode are superposed on a transparent substrate. Light generated inthe light emitting layer repeats reflections between the multilayermirror and the metal electrode and resonates therebetween.

In another preferred embodiment, each of a transparent orsemi-transparent electrode and a metal electrode functions as areflector on a transparent substrate, and light generated in the lightemitting layer repeats reflection and resonates therebetween.

In order to form a resonance structure, the effective refractive indexof two reflectors and the optical path length determined from therefractive index and thickness of each layer between the reflectors areadjusted to optimal values for obtaining a desired resonance wavelength.The calculation formula in the case of the first embodiment is describedin Japanese Patent Application Laid-Open No. Hei 9-180883, and thecalculation formula in the case of the second embodiment is described inJapanese Patent Application Laid-Open No. 2004-127795.

(Use of Luminescence Device of the Present Invention)

The luminescence device of the present invention may be suitably usedfor light emission apparatuses, pixels, display devices, displays,backlights, electrophotography, illumination light sources, recordinglight sources, exposure light sources, reading light sources,indicators, signboards, interiors, optical communication, or the like.Particularly, the luminescence device of the present invention ispreferably used for a device that is driven in a region of high lightemission luminance intensity, such as illumination apparatus and displayapparatus.

Next, the light emission apparatus of the present invention is describedbelow with reference to FIG. 2.

The light emission apparatus of the present invention uses theabove-described organic electroluminescence device.

FIG. 2 is a sectional view schematically showing one exemplary exampleof the light emission apparatus of the present invention.

The light emission apparatus 20 of FIG. 2 is composed of a substrate(supporting substrate) 2, an organic electroluminescence device 10, asealing container 16 and the like.

The organic electroluminescence device 10 is configured by sequentiallystacking an anode (first electrode) 3, an organic layer 11 and a cathode(second electrode) 9 on a substrate 2. A protective layer 12 is stackedon the cathode 9, and a sealing container 16 is provided on theprotective layer 12 through an adhesion layer 14. Also, a part ofelectrodes 3 and 9, a partition wall, an insulating layer and the likeare omitted.

Herein, as for the adhesion layer 14, a photocurable or thermosettingadhesive such as epoxy resin may be used and, for example, athermosetting adhesive sheet may also be used.

The light emission apparatus of the present invention is notparticularly limited in its application and, for example, may be usednot only as an illumination apparatus but also a display apparatus of atelevision set, a personal computer, a cellular phone, an electronicpaper and the like.

Then, the illumination apparatus according to an embodiment of thepresent invention is described below with reference to FIG. 3.

FIG. 3 is a sectional view schematically showing one exemplary exampleof the illumination apparatus according to an embodiment of the presentinvention.

The illumination apparatus 40 according to an embodiment of the presentinvention includes, as shown in FIG. 3, the above-described organic ELdevice 10 and a light scattering member 30. More specifically, theillumination apparatus 40 is configured so that the substrate 2 of theorganic EL device 10 and the light scattering member 30 are put intocontact.

The light scattering member 30 is not particularly limited as long asthe member is capable of scattering light, but in FIG. 3, a memberobtained by dispersing fine particles 32 in a transparent substrate 31is used. Suitable examples of the transparent substrate 31 include aglass substrate. Suitable examples of the fine particles 32 includetransparent resin fine particles. As the glass substrate and thetransparent resin fine particles, known products may be used for both.In such an illumination apparatus 40, when light emitted from theorganic electroluminescence device 10 is incident on the light incidentsurface 30A of the scattering member 30, the incident light is scatteredby the light scattering member 30 and the scattered light is output asilluminating light from the light output surface 30B.

EXAMPLE

Hereinafter, the present invention will be described in detail withreference to Examples, but the present invention is not limited thereto.

The compound represented by Formula (Ch-1) used in the followingExamples was prepared with reference to Internal Publication No.WO09/008,311. For example, an exemplary compound C-1 may be prepared bya method described in [0122] of Internal Publication No. WO09/008,311using a 6,12-dibromochrysene and a 4-(2-naphthyl)phenyl borate asstarting materials. In addition, a compound C-2 may be prepared by amethod described in [0121] of the same patent document using a6,12-dibromochrysene and a 4-(1-naphthyl)phenyl borate as startingmaterials. Further, the compound represented by Formula (PQ-1) may beprepared by using a method described in US Patent Application No.2008/0261076. For example, P-1 may be prepared by a method described in[0064] to [0067] of US Patent Application No. 2008/0261076.

Comparative Example 1-1

A glass substrate having an ITO film with a thickness of 0.5 mm and eachside of 2.5 cm in square (manufactured by Geomatec Co., Ltd., andsurface resistance 10Ω/□ (square)) was put into a washing container,ultrasonically washed in a 2-propanol, followed by UV-ozone treatmentfor 30 min. The following organic layers were sequentially vapordeposited on this transparent anode (ITO film) by means of vacuumdeposition.

First layer: HTL-1: film thickness 65 nm

Second layer: Dopant: RD-1 (5 mass %), host material: C-1 (95 mass %):film thickness 40 nm

Third layer: ETL-1: film thickness 10 nm

Fourth layer: Alq (tris(8-hydroxyquinoline) aluminum complex): filmthickness 30 nm

Fifth layer: Reductive dopant: Li (40 mass %), Alq (60 mass %): filmthickness 0.5 nm

Metal aluminum was vapor deposited thereon to 150 nm, thereby forming acathode.

The resultant laminate was placed in a glove box substituted with argongas without being in contact with the atmosphere, and sealed using astainless-made sealing can and a UV-curable adhesive (XNR5516HV,manufactured by Nagase-CHIBA Ltd.) to obtain a comparative device 1-1.

Examples 1-1 to 1-22 and Comparative Examples 1-2 to 1-16

Various devices were obtained in the same manner as described inComparative Example 1-1, except that constituting materials of thesecond layer were changed into compositions shown in the following Table1.

TABLE 1 Evaluation of device configuration 1 Difference EML DrivingDriving in voltage Dopant voltage durability increment Device No. HTLHost (Conc. %) ETL EQE (%) (V) (H) (V) Comparative Device 1-1 HTL-1(65)C-1 RD-1(5) ETL-1 10.4 7.3 11000 1.4 Comparative Device 1-2 HTL-1(65)C-1 RD-2(5) ETL-1 10.6 7.6 13000 1.3 Comparative Device 1-3 HTL-1(65)C-1 RD-3(5) ETL-1 10.6 7.4 12000 1.3 Comparative Device 1-4 HTL-1(65)C-1 RD-4(5) ETL-1 11.0 7.0 9000 1.8 Comparative Device 1-5 HTL-1(65) C-1RD-5(5) ETL-1 9.2 7.3 7500 2.4 Comparative Device 1-6 HTL-1(65) C-1RD-6(5) ETL-1 7.2 8.7 4900 3.4 Comparative Device 1-7 HTL-1(65) C-3RD-1(5) ETL-1 9.5 7.4 9500 1.4 Comparative Device 1-8 HTL-1(65) C-3RD-2(5) ETL-1 9.6 7.7 9600 1.4 Comparative Device 1-9 HTL-1(65) C-3RD-3(5) ETL-1 10.0 7.6 9600 1.3 Comparative Device 1-10 HTL-1(65) C-3RD-4(5) ETL-1 10.2 7.5 6800 1.9 Comparative Device 1-11 HTL-1(65) C-3RD-5(5) ETL-1 8.9 7.4 6300 2.5 Comparative Device 1-12 HTL-1(65) BalqP-1(5) ETL-1 13.1 8.0 15000 1.7 Comparative Device 1-13 HTL-1(65) Host-TP-1(5) ETL-1 12.0 7.4 15000 1.6 Comparative Device 1-14 HTL-1(65) BalqP-13(5) ETL-1 11.0 8.0 11000 1.9 Comparative Device 1-15 HTL-1(65)Host-T P-13(5) ETL-1 11.1 7.6 12000 2.0 Comparative Device 1-16HTL-1(65) BAlq RD-1(5) ETL-1 8.5 7.7 7500 3.1 Inventive Device 1-1HTL-1(65) C-1 P-1(5) ETL-1 15.2 6.5 24000 0.7 Inventive Device 1-2HTL-1(65) C-1 P-3(5) ETL-1 14.4 6.6 21000 0.8 Inventive Device 1-3HTL-1(65) C-1 P-13(5) ETL-1 14.1 6.5 18000 0.7 Inventive Device 1-4HTL-1(65) C-2 P-1(5) ETL-1 14.3 6.7 18000 0.9 Inventive Device 1-5HTL-1(65) C-2 P-2(5) ETL-1 13.8 6.8 21000 0.8 Inventive Device 1-6HTL-1(65) C-2 P-8(5) ETL-1 14.1 6.9 24000 0.9 Inventive Device 1-7HTL-1(65) C-3 P-1(5) ETL-1 14.7 6.4 23000 0.7 Inventive Device 1-8HTL-1(65) C-3 P-4(5) ETL-1 14.3 6.6 18000 0.8 Inventive Device 1-9HTL-1(65) C-3 P-12(5) ETL-1 14.0 6.8 19000 0.9 Inventive Device 1-10HTL-1(65) C-7 P-1(5) ETL-1 14.6 6.6 20000 0.9 Inventive Device 1-11HTL-1(65) C-7 P-14(5) ETL-1 14.4 6.7 19000 0.9 Inventive Device 1-12HTL-1(65) C-7 P-15(5) ETL-1 13.9 7.0 17000 0.9 Inventive Device 1-13HTL-1(65) C-4 P-5(5) ETL-1 13.8 6.9 17000 0.8 Inventive Device 1-14HTL-1(65) C-11 P-6(5) ETL-1 14.5 6.6 19000 0.8 Inventive Device 1-15HTL-1(65) C-12 P-7(5) ETL-1 14.5 6.7 20000 0.8 Inventive Device 1-16HTL-1(65) C-14 P-9(5) ETL-1 14.9 7.0 21000 0.9 Inventive Device 1-17HTL-1(65) C-16 P-10(5) ETL-1 13.8 6.4 16000 1.0 Inventive Device 1-18HTL-1(65) C-17 P-11(5) ETL-1 13.9 7.0 17000 0.9 Inventive Device 1-19HTL-1(65) C-19 P-1(5) ETL-1 15.0 6.5 23000 0.7 Inventive Device 1-20HTL-1(65) C-28 P-8(5) ETL-1 15.1 7.1 18000 0.9 Inventive Device 1-21HTL-2(65) C-1 P-1(5) ETL-1 15.1 6.5 22000 0.7 Inventive Device 1-22HTL-1(65) C-1 P-1(5) ETL-2 15.0 6.6 21000 0.7

Comparative Example 2-1

A glass substrate having an ITO film having a thickness of 0.5 mm andeach side of 2.5 cm in square (manufactured by Geomatec Co., Ltd., andsurface resistance 10Ω/□ (square)) was put into a washing container,ultrasonically washed in 2-propanol, followed by UV-ozone treatment for30 min. The following organic layers were sequentially vapor depositedon this transparent anode (ITO film) by means of vacuum deposition.

First layer: HTL-1: film thickness 10 nm

Second layer: NPD: film thickness 40 nm

Third layer: Dopant: P-1 (6 mass %), host material: BAlq (94 mass %):film thickness 40 nm

Fourth layer: Alq: film thickness 35 nm

Then, 0.2 nm of lithium fluoride and 70 nm of metal aluminum were vapordeposited in this order thereon, thereby forming a cathode.

The resultant laminate was placed in a glove box substituted with argongas without being in contact with the atmosphere, and sealed using astainless-made sealing can and a UV-curable adhesive (XNR5516HV,manufactured by Nagase-CHIBA Ltd.) to obtain a comparative device 2-1.

Examples 2-1 to 1-21 and Comparative Examples 2-2 to 2-8

Various devices were obtained in the same manner as described inComparative Example 2-1, except that constituting materials of the thirdlayer were changed into compositions shown in the following Table 2.

TABLE 2 Evaluation of device configuration 2 Difference EML DrivingDriving in voltage Dopant voltage Durability increment Evaluation ofDevice No. Host (Conc. %) EQE (%) (V) (H) (V) Comparative Device 2-1Balq P-1(6) 14.7 8.3 14000 1.6 Comparative Device 2-2 Host-T P-1(6) 14.07.8 12000 1.8 Comparative Device 2-3 Balq P-13(6) 14.4 8.2 11000 1.5Comparative Device 2-4 Host-T P-13(6) 13.5 7.8 11000 1.7 ComparativeDevice 2-5 C-1 RD-3(6) 15.0 8.0 14000 1.9 Comparative Device 2-6 C-1RD-4(6) 12.8 7.8 8500 1.7 Comparative Device 2-7 C-1 RD-5(6) 13.2 8.37000 1.8 Comparative Device 2-8 C-1 RD-6(6) 11.7 9.1 4900 2.2 InventiveDevice 2-1 C-1 P-1(6) 18.5 7.4 23000 0.7 Inventive Device 2-2 C-1 P-2(6)18.0 7.6 22000 0.8 Inventive Device 2-3 C-1 P-7(6) 18.1 7.6 20000 0.8Inventive Device 2-4 C-1 P-8(6) 18.0 7.6 19000 0.8 Inventive Device 2-5C-1 P-11(6) 17.6 7.5 18000 0.9 Inventive Device 2-6 C-2 P-1(6) 18.4 7.520000 0.8 Inventive Device 2-7 C-2 P-3(6) 17.8 7.6 19000 0.8 InventiveDevice 2-8 C-2 P-4(6) 17.8 7.7 19000 0.9 Inventive Device 2-9 C-3 P-1(6)18.3 7.3 25000 0.9 Inventive Device 2-10 C-3 P-5(6) 16.5 7.8 18000 1.0Inventive Device 2-11 C-3 P-13(6) 17.8 7.4 18000 0.8 Inventive Device2-12 C-11 P-1(6) 18.2 7.3 21000 0.9 Inventive Device 2-13 C-11 P-8(6)17.7 7.7 19000 0.9 Inventive Device 2-14 C-11 P-13(6) 17.6 7.5 18000 0.8Inventive Device 2-15 C-6 P-5(6) 16.9 7.9 15000 0.8 Inventive Device2-16 C-9 P-9(6) 17.1 8.0 17000 0.9 Inventive Device 2-17 C-10 P-10(6)17.9 7.7 17000 0.9 Inventive Device 2-18 C-12 P-14(6) 17.8 7.6 19000 0.8Inventive Device 2-19 C-15 P-14(6) 18.0 8.0 18000 0.9 Inventive Device2-20 C-24 P-1(6) 17.6 7.8 19000 0.8 Inventive Device 2-21 C-27 P-8(6)17.3 7.5 17000 0.9

Example 3-1 and Comparative Example 3-1

As for Compound C-1 and BAlq, thin films were fabricated from samplessubjected to sublimation purification once and samples subjected tosublimation purification three times in the following method, and thenthermally stimulated current was measured. Herein, the samples subjectedto sublimation purification once are the same as C-1 and BAlq used forthe devices described in Table 1 and Table 2.

(Evaluation of Materials Using Thermally Stimulated Current Measurement)

(a) A substrate of a glass plate on which an ITO film (film thickness0.2 μm) is formed was washed with isopropyl alcohol and subjected toUV-ozone treatment for 30 minutes, thereby forming a transparentelectrode. On the transparent electrode, a film with a thickness of 100nm was formed from a test compound by vacuum deposition. Further, a filmwith a thickness of 250 nm was formed on the thin film from aluminum,thereby forming a counter electrode.

(b) Measurement of Thermally Stimulated Current

The thermally stimulated current of each thin film sample was measuredby a thermally stimulated current analyzer, TS-FETT, available fromRigaku Denki Co., Ltd. Each thin film sample was cooled to 93 K at arate of 5 K/min and maintained at this temperature for 20 minutes. Next,light with a λ_(max)=330 nm (using xenon lamp light passed through aband pass filter) is irradiated to the sample for 5 minutes whilemaintaining 93K. Then, temperature was increased to 200K at a rate of 10K/min while applying a bias of 0.5V, and the current flowing at thattime was measured.

As a result, C-1 and BAlq subjected to sublimation purification once hada peak current value between 100K and 150K, while C-1 and BAlq subjectedto sublimation purification three times had no peak current valuebetween 100K and 150K.

For the inventive device 1-1 and the comparative device 1-11 describedin Table 1, the similar devices were fabricated using samples of C-1 andBAlq having no peak current value between 100K and 150K, therebyproviding a device 3-1 of the present invention and a comparative device3-1, respectively. In the column of thermally stimulated current shownin Table 3, a sign A and a sign B represent a case having no peakcurrent value and a case having a peak current, between 100K and 150K,respectively.

TABLE 3 TSC condition and device characteristics Difference EML DrivingDriving in voltage Thermally Host Dopant EQE Voltage durabilityincrement stimulated Device No. (TSC condition) (Conc. %) (%) (V) (H)(V) current Inventive Device 1-1 C-1 P-1(5) 15.2 6.5 24000 0.7 BInventive Device 3-1 C-1 P-1(5) 15.8 6.3 35000 0.7 A Comparative Device1-11 Balq P-1(5) 13.1 8.0 15000 1.7 B Comparative Device 3-1 Balq P-1(5)13.0 7.8 16000 1.8 A

Comparative Example 4-1

A glass substrate having an indium tin oxide (ITO) film having athickness of 0.5 mm and each side of 2.5 cm in square (manufactured byGeomatec Co., Ltd., and surface resistance 10Ω/□ (square)) was put intoa washing container, ultrasonically washed in 2-propanol, followed byUV-ozone treatment for 30 min. After carrying out spin coating ofaqueous dispersion of poly(ethylene dioxythiophene) and polystyrenesulfonate (Baytron P available from BAYER: solid content 1.3%) on thetransparent anode (ITO film), vacuum drying is performed at 150° C. for2 hours, thereby forming a PEDOT-PSS layer (first layer) with athickness of 100 nm.

The following organic layers were sequentially vapor deposited on thefirst layer by means of vacuum deposition.

Second layer: HTL-1: film thickness 10 nm

Third layer: NPD: film thickness 40 nm

Fourth layer: Dopant: P-1 (6 mass %), host material: BAlq (94 mass %):film thickness 40 nm

Fifth layer: Alq: film thickness 35 nm

Then, 0.2 nm of lithium fluoride and 70 nm of metal aluminum were vapordeposited in this order thereon, thereby forming a cathode.

The resultant laminate was placed in a glove box substituted with argongas without being in contact with the atmosphere, and sealed using astainless-made sealing can and a UV-curable adhesive (XNR5516HV,manufactured by Nagase-CHIBA Ltd.) to obtain a comparative device 4-1.

Examples 4-1 to 4-21 and Comparative Examples 4-2 to 4-8

Various devices were obtained in the same manner as described inComparative Example 4-1, except that constituting materials of thefourth layer were changed into compositions shown in the following Table4.

TABLE 4 Difference EML Driving Driving in voltage Dopant voltageDurability increment Evaluation of Device No. Host (Conc. %) EQE (%) (V)(H) (V) Comparative Device 4-1 Balq P-1(6) 11.5 8.2 2500 1.7 ComparativeDevice 4-2 Host-T P-1(6) 11.0 7.8 1800 1.9 Comparative Device 4-3 BalqP-13(6) 11.1 8.1 1400 1.6 Comparative Device 4-4 Host-T P-13(6) 11.0 7.91300 1.9 Comparative Device 4-5 C-1 RD-3(6) 12.0 8.1 1300 2.1Comparative Device 4-6 C-1 RD-4(6) 9.5 8.2 2000 1.7 Comparative Device4-7 C-1 RD-5(6) 10.2 8.3 2100 1.9 Comparative Device 4-8 C-1 RD-6(6) 8.79.0 1500 2.4 Inventive Device 4-1 C-1 P-1(6) 14.0 7.3 4800 0.8 InventiveDevice 4-2 C-1 P-2(6) 14.2 7.3 4600 0.8 Inventive Device 4-3 C-1 P-7(6)14.1 7.4 5000 0.8 Inventive Device 4-4 C-1 P-8(6) 14.3 7.6 4900 0.8Inventive Device 4-5 C-1 P-11(6) 13.8 7.5 4800 0.8 Inventive Device 4-6C-2 P-1(6) 14.3 7.4 5000 0.8 Inventive Device 4-7 C-2 P-3(6) 14.1 7.75000 0.7 Inventive Device 4-8 C-2 P-4(6) 13.9 7.8 5100 0.8 InventiveDevice 4-9 C-3 P-1(6) 14.0 7.3 5300 0.9 Inventive Device 4-10 C-3 P-5(6)12.9 7.5 4600 1.1 Inventive Device 4-11 C-3 P-13(6) 15.0 7.2 4500 0.9Inventive Device 4-12 C-11 P-1(6) 14.5 7.3 5000 0.9 Inventive Device4-13 C-11 P-8(6) 13.7 7.8 4900 0.9 Inventive Device 4-14 C-11 P-13(6)14.6 7.4 4700 0.8 Inventive Device 4-15 C-6 P-5(6) 13.8 7.6 4600 0.9Inventive Device 4-16 C-9 P-9(6) 13.9 7.7 4500 0.7 Inventive Device 4-17C-10 P-10(6) 13.9 7.5 4600 0.9 Inventive Device 4-18 C-12 P-14(6) 14.07.4 4700 0.7 Inventive Device 4-19 C-15 P-14(6) 14.2 7.9 4800 0.8Inventive Device 4-20 C-24 P-1(6) 13.7 7.9 4700 0.9 Inventive Device4-21 C-27 P-8(6) 13.5 7.8 4600 0.9

(Evaluation of Performance of Organic Electroluminescence Devices)

(a) External Quantum Efficiency

DC voltage was applied to each device by using a Source Measure Unit2400 manufactured by Toyo Technica Corporation to enable the devices toemit light, and the luminance intensity was measured by using aluminance meter BM-8 manufactured by TOPCON CORPORATION. Emissionspectra and emission wavelengths were measured by using a spectrumanalyzer PMA-11 manufactured by Hamamatsu Photonics K.K. On the basis ofthe obtained numerical values, the external quantum efficiency in thevicinity of the luminance intensity of about 1000 cd/m² was calculatedby a luminance intensity conversion method.

(b) Driving Voltage

DC voltage was applied to each device so that the luminance intensitywas 1000 cd/m², thereby enabling the device to emit light. The voltageapplied at that time was defined as an index for evaluating drivingvoltage.

(c) Driving Durability

DC voltage was applied to each device so that luminance intensity was1000 cd/m², and then the time until the luminance intensity decreased to500 cd/m² was measured. The measured time was defined as an index forevaluating driving durability.

(d) Difference in Voltage Increment Depending on Difference in DrivingTemperature

The difference (V) in voltage increment when each device reaches aluminance intensity of 500 cd/m² after being driven at 25° C. to 20° C.under an initial luminance intensity of 1000 cd/m² was used as an index.

From the results of Table 1 and Table 2, it can be seen that the deviceof the present invention using a host material represented by Formula(Ch-1) and a specific iridium complex represented by Formula (PQ-1) in alight emitting layer has excellent external quantum efficiency anddriving durability, and shows a small difference in voltage incrementeven at a different driving temperature, as compared to the devices ofthe Comparative Examples.

In addition, it can be seen from the results of Table 3 that when usinga sample in which a compound represented by Formula (Ch-1) has no peakcurrent value at 100K to 150K as determined by thermally stimulatedcurrent of a thin film formed to a film thickness of 100 nm by vacuumdeposition of the compound, durability is significantly improved. Whenthe host material is BAlq, improvement of durability is low.

Further, it can be seen from the results of Table 4 that even when anyone layer of organic layers is formed by a coating process, the deviceof the present invention using a host material represented by Formula(Ch-1) and a specific iridium complex represented by Formula (PQ-1) in alight emitting layer has excellent external quantum efficiency anddriving durability, and shows a small difference in voltage incrementeven at a different driving temperature, as compared to the devices ofthe Comparative Examples.

It is required for light emission apparatuses, display apparatuses andillumination apparatuses to emit light in a moment with high luminousefficiency, and thus the luminance device of the present inventiondesigned to show increased luminous efficiency in such cases may be usedadvantageously.

In addition, the device of the present invention has excellent luminousefficiency or durability even when the device is used in a hightemperature environment, such as in-vehicle use, and is suitable forlight emission apparatuses, display apparatuses and illuminationapparatuses.

Structures of the compounds used in the Examples and the ComparativeExample are shown below.

Compounds appeared in Examples

Abbreviations in Tables are as follows.

HIL: hole injection layer or first layer

HTL: hole transporting layer or second layer

EML: light emitting layer or third layer

ETL: electron transporting layer or fourth layer

EQE: external quantum efficiency

INDUSTRIAL APPLICABILITY

The organic electroluminescence device of the present invention has lowelectric power consumption and high external quantum efficiency, andshows excellent durability. Moreover, the organic electroluminescencedevice of the present invention has a small difference in voltageincrement even at a different driving temperature, and realizes stableperformance for the use of which the driving durability is required in ahigh temperature environment, such as in-vehicle use.

Although the present invention has been described with reference todetailed and specific embodiments thereof, it is obvious to thoseskilled in the art that various changes or modifications may be madewithout departing from the spirit and scope of the present invention.

This application claims priority from Japanese Patent Application(Japanese Patent Application No. 2010-007537) filed on Jan. 15, 2010,the disclosure of which is incorporated herein by reference in itsentirety.

EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS

-   -   2: Substrate    -   3: Anode    -   4: Hole injection layer    -   5: Hole transporting layer    -   6: Light emitting layer    -   7: Hole blocking layer    -   8: Electron transporting layer    -   9: Cathode    -   10: Organic electroluminescence device (organic EL device)    -   11: Organic layer    -   12: Protective layer    -   14: Adhesive layer    -   16: Sealing container    -   20: Light emission apparatus    -   30: Light scattering member    -   31: Transparent substrate

30A: Light incident surface

-   -   30B: Light reflecting surface    -   32: Fine particles    -   40: Illumination apparatus

The invention claimed is:
 1. A light emitting organic thin filmcomprising at least one compound represented by Formula (PQ-1) and atleast one compound represented by Formula (Ch-1):

wherein each of R^(a), R^(b) and R^(c) independently represents ahydrogen atom or an alkyl group, any one of R^(a), R^(b) and R^(c)represents a hydrogen atom, and the remaining two represent an alkylgroup, each of R¹ to R⁵ independently represents a hydrogen atom, analkyl group, an aryl group, a fluorine atom or a cyano group, each ofR^(x) and R^(y) independently represents an alkyl group or a phenylgroup, each of R¹⁰¹ to R¹¹⁰ independently represents a hydrogen atom, analkyl group, a cycloalkyl group or an aryl group, each of R¹¹¹ to R¹¹⁵independently represents a hydrogen atom, an alkyl group, a cycloalkylgroup or an aryl group, provided that any one of R¹¹¹ to R¹¹⁵ representsa condensed hydrocarbyl group that may have a substituent Z, each ofR¹²¹ to R¹²⁵ independently represents a hydrogen atom, an alkyl group, acycloalkyl group or an aryl group, provided that any one of R¹²¹ to R¹²⁵represents a condensed hydrocarbyl group that may have a substituent Z,and the substituent Z represents an alkyl group, an alkenyl group, aphenyl group, an aromatic heterocyclic group, an alkoxy group, a phenoxygroup, a fluorine atom, a silyl group, an amino group, a cyano group ora combination thereof, and a plurality of substituents Z may be bondedto each other to form an aryl ring.
 2. The light emitting organic thinfilm according to claim 1, wherein the compound represented by Formula(Ch-1) has no peak current value at 100K to 150K as determined bythermally stimulated current of a thin film formed to a film thicknessof 100 nm by vacuum deposition of the compound.
 3. The light emittingorganic thin film according to claim 1, wherein two of R^(a), R^(b) andR^(c) represent a methyl group and the remaining one represents ahydrogen atom.
 4. The light emitting organic thin film according toclaim 3, wherein R¹ to R⁵ represent a hydrogen atom.
 5. The lightemitting organic thin film according to claim 1, wherein R^(a) and R^(c)represent an alkyl group, and R^(b) represents a hydrogen group.
 6. Thelight emitting organic thin film according to claim 1, wherein R¹⁰¹ toR¹¹⁰ represent a hydrogen atom.
 7. The light emitting organic thin filmaccording to claim 1, wherein any one of R¹¹¹ to R¹¹⁵ represents anaphthyl or a phenanthryl group and the others represent a hydrogenatom, and any one of R¹²¹ to R¹²⁵ represents a naphthyl or a phenanthrylgroup and the others represent a hydrogen atom.
 8. The light emittingorganic thin film according to claim 1, wherein R^(a) and R^(c)represent an alkyl group and R^(b) represents a hydrogen group, and anyone of R¹¹¹ to R¹¹⁵ represents a naphthyl or a phenanthryl group and theothers represent a hydrogen atom, and any one of R¹²¹ to R¹²⁵ representsa naphthyl or a phenanthryl group and the others represent a hydrogenatom.
 9. The light emitting organic thin film according to claim 1,wherein a content of Cl, Br and I contained in the light emittingorganic thin film is 100 ppm or less.
 10. A composition comprising acompound represented by Formula (PQ-1) and a compound represented byFormula (Ch-1):

wherein each of R^(a), R^(b) and R^(c) independently represents ahydrogen atom or an alkyl group, any one of R^(a), R^(b) and R^(c)represents a hydrogen atom, and the remaining two represent an alkylgroup, each of R¹ to R⁵ independently represents a hydrogen atom, analkyl group, an aryl group, a fluorine atom or a cyano group, each ofR^(x) and R^(y) independently represents an alkyl group or a phenylgroup, each of R¹⁰¹ to R¹¹⁰ independently represents a hydrogen atom, analkyl group, a cycloalkyl group or an aryl group, each of R¹¹¹ to R¹¹⁵independently represents a hydrogen atom, an alkyl group, a cycloalkylgroup or an aryl group, provided that any one of R¹¹¹ to R¹¹⁵ representsa condensed hydrocarbyl group that may have a substituent Z, each ofR¹²¹ to R¹²⁵ independently represents a hydrogen atom, an alkyl group, acycloalkyl group or an aryl group, provided that any one of R¹²¹ to R¹²⁵represents a condensed hydrocarbyl group that may have a substituent Z,and the substituent Z represents an alkyl group, an alkenyl group, aphenyl group, an aromatic heterocyclic group, an alkoxy group, a phenoxygroup, a fluorine atom, a silyl group, an amino group, a cyano group ora combination thereof, and a plurality of substituents Z may be bondedto each other to form an aryl ring.
 11. An organic electroluminescencedevice comprising: a pair of electrodes; and an organic layer includinga light emitting layer disposed between the electrodes, on a substrate,wherein the light emitting layer is the light emitting organic thin filmaccording to claim
 1. 12. The organic electroluminescence deviceaccording to claim 11, wherein at least one layer of the organic layeris formed by a coating process using a solution or dispersion.
 13. Adisplay apparatus using the organic electroluminescence device accordingto claim
 11. 14. An illumination apparatus using the organicelectroluminescence device according to claim
 11. 15. An organicelectroluminescence device comprising: a pair of electrodes; and anorganic layer including a light emitting layer disposed between theelectrodes, on a substrate, wherein the light emitting layer is thelight emitting organic thin film according to claim 1, and the compoundrepresented by Formula (Ch-1) of claim 1 has no peak current value at100K to 150K as determined by thermally stimulated current of a thinfilm formed to a film thickness of 100 nm by vacuum deposition of thecompound.